Pictures from the scene showed them lying on a big heap at the Barton 1792 Distillery in Bardstown.
The structure, which has holding about 20,000 barrels, suffered major damage.
It is not known what caused the incident at warehouse No 30 but no injuries were reported.
“We are assessing how many of the impacted barrels can be recovered,” said Amy Preske, a spokeswoman for Sazerac, a Louisiana-based spirits company.
“A mix of various distilled products at various ages were stored in that warehouse.”
Bardstown Fire Chief Bill Mattingly said the warehouse, which is on a steep hill, collapsed “length-wise”, and left the other half-leaning and in danger of buckling, the Kentucky Standard reported.
He said: “We’re trying to determine why it collapsed. There was nobody in the building at the time. We’re very fortunate in that.”
Mr Mattingly said there was a 3.5m (12ft)-deep basement under the warehouse, and the emergency services hoped most of the whiskey went into it.
There are concerns that some of the whiskey could have flowed into nearby groundwater. Early tests proved negative for the alcohol.
John Mura, a spokesman for Kentucky’s energy and environment cabinet, said: “There is a stream of bourbon and water running down the hillside that has taken much time to properly and thoroughly assess.”
The spill has affected nearby Withrow Creek, a tributary to Beech Fork, but “it appears to be minimal,” he said, according to The New York Times.
The Barton distillery, established in 1879, includes 29 storage warehouses and 22 other buildings, according to its website.